DESCRIPTION: (from Abstract) The long term objective of the current proposal is the attainment of a greater understanding of the functional organization of the basal ganglia. Substantial evidence suggests that many neurological and psychiatric disorders, including Parkinson's disease, Huntington's disease, Sydenham's chorea, torsion dystonia, Tourette's syndrome and schizophrenia, may result from abnormalities in the activity of these nuclei. Progress in understanding the etiology of these disorders, and in developing treatments for them, is largely dependent on advances in understanding the basic nature of basal ganglia functioning. The proposed experiments are designed to examine basal ganglia by using the immunocytochemical detection of immediate early genes (IEGs) as markers for neurons affected by various behavioral or pharmacological manipulations. The striatum is the largest nucleus within the basal ganglia and is the primary terminus of input into this system. The first set of studies will examine the pharmacological and behavioral control of IEG expression within this structure with emphasis on the patterning of IEG expression with respect to the striosome/matrix compartmentation of the striatum. The striatum contains a number of neuroactive compounds including dopamine, serotonin, adenosine, acetylcholine and substance P and the role played by these substances in controlling striatal IEG expression will be examined. The applicants will also examine the role of dopamine in IEG expression induced by shuttling behavior and characterize the cells that express IEGs under these conditions. Events occurring within the striatum can only influence behavior by affecting the activity of neurons within other parts of the brain. The second group of studies will therefore use IEG expression as a tool to investigate the basic organization of extrastriatal circuitry related to the basal ganglia. Experiments will examine the ability drugs microinjected directly into the striatum, or other basal ganglia nuclei, to influence IEG expression at extrastriatal sites. Other studies will examine the effects of lesions within the basal ganglia on the IEG expression induced by systemic administration of dopaminergic drugs.